Infusion ports for the infusion and/or withdrawal of fluids from a patient are well-known, secured to the proximal end of an implanted catheter. These ports are typically used for drug infusion or small amounts of blood withdrawal, where large flows of fluid are not required. The ports are assemblies of a housing with a discharge port in fluid communication with the catheter and the reservoir within the port housing, and provide a subcutaneous self-sealing septum that defines an access site for multiple needle sticks through the covering skin tissue of the patient, through the septum and into the reservoir, without the need to continuously search for new access sites. Examples of such ports are disclosed, for example, in U.S. Pat. Nos. 4,704,103; 4,762,517; 4,778,452; 5,185,003; 5,213,574; 5,637,102 and 6,113,572.
United States Patent Publication No. US 2007/0219510, partially assigned to the assignee hereof, discloses a venous access port having a needle-impenetrable housing and a needle-penetrable septum enabling infusion of fluid into the port, providing an interior reservoir and a passageway extending from the reservoir through a stem of a discharge port to establish fluid communication with a proximal end of a catheter lumen to which the port assembly is secured prior to placement of the assembly into a patient. The discharge port is defined by a discharge stem extending from the port assembly and is adapted to be inserted into the lumen of the proximal end of a catheter that extends into the vasculature of the patient. The discharge stem defines a pair of barbed protuberances onto which the catheter lumen wall grips tightly when the stem is fully inserted into the catheter proximal end. This is seen in FIGS. 1 to 4 hereof. FIGS. 3 and 4 depict generally the procedure of locking a catheter proximal end onto the discharge stem using a locking sleeve.
United States Patent Publication No. US 2007/0270770, assigned to the assignee hereof, discloses a venous access port having a housing and a septum, providing an interior reservoir and a passageway extending from the reservoir through a stem of a discharge port to establish fluid communication with a proximal end of a catheter lumen to which the port assembly is secured prior to placement of the assembly into a patient. The housing includes a base and a cap that together cooperate to secure a needle-penetrable septum within the assembly by compressing a seating flange of the septum in a seat of the housing base. The cap is mechanically secured to the housing base by a mechanical joint and solvent bonding. As in the port discussed above, the discharge port is defined by a discharge stem extending from the port assembly and is adapted to be inserted into the lumen of the proximal end of a catheter that extends into the vasculature of the patient. The discharge stem defines a pair of rounded protuberances onto which the catheter lumen wall grips tightly when the stem is fully inserted into the catheter proximal end. This is seen in FIGS. 13 and 14 hereof.
It is important to provide a venous access port assembly that provides an assured locking connection between the discharge stem and the catheter. U.S. Pat. No. 6,113,572 sets forth a connection system between a catheter's proximal end and a venous access port assembly at a discharge stem thereof. The rigid, tubular stem has a plurality of engagement barbs encircling and radially outwardly extending on an exterior surface of the stem. A compression sleeve is loosely disposed along the catheter, and the catheter's proximal end is first urged onto and over the engagement barbs, and then the compression sleeve is urged from its loose position over the catheter end fitted onto the discharge stem thus lockingly and sealingly securing the catheter to the discharge stem, in one embodiment for one type of catheter made of silicone material. For a catheter of polyurethane material, a compression sleeve is fitted onto a length of tubing larger in inner diameter than the catheter's outer diameter; when the catheter is force-fit onto the barbed discharge stem, the sleeve/tubing component is moved proximally over the catheter end, compressing the catheter lockingly and sealingly onto the discharge stem. In both embodiments, the engagement barbs have sharply defined proximal edges at their end faces against which the catheter lumen wall is firmly pressed by the locking system. The two types of connection systems are sold together with the venous access port assembly to enable the practitioner to select the appropriate one depending on the catheter selected by the practitioner.
It is desired to provide a catheter/device connection system that does not press the catheter wall directly against sharp edges of engagement barbs.